Don Edwards San Francisco Bay National Wildlife Refuge, Fish and Wildlife Service

Black Rail, cont.

What threats do these remnant populations face? What does the future hold? The remnant tidal marshlands of San Francisco Bay occupy only 15% or less of their historic area, yet even in such diminished capacity encompass 90% of all remaining California tidal marshes. Besides direct loss of habitat, other threats that could potentially alter or degrade tidal wetlands include freshwater inflow diversions from the North Bay, progressive rises in sea level, and toxic agent contaminations that have been shown to have adverse biological effects on other birds in the estuary. Indeed, during the course of our studies several oil spills occurred in bayshore marshes in Suisun Bay.

The trend in land-use policy around San Francisco Bay, and much of the rest of the country, is toward marsh restoration and wetland enhancement. As the pressures of urbanization and human economics inevitable increase, the habitat values of fully protected marshes will also increase. As wetlands are restored to their natural functions, the inclusion of a zone of transitional upland vegetation around the marsh periphery may insure that as rails colonize these new sites, they may be able to persist and maintain viable populations.

About the author: As a field biologist, Jules Evens has conducted studies in Bay Area wetlands since the early 1980's. He is currently engaged in the assessment of habitat requirements for a variety of bird species, developing habitat restoration and management plans, and monitoring wetland restoration projects. He is the author of The Natural History of the Point Reyes Peninsula and has written articles on a variety of subjects. Jules is a research associate of Point Reyes Bird Observatory and Audubon Canyon Ranch and has his own consulting business, Avocet Research Associates. He can be contacted via E-mail at <avocetra@aol.com>

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Last updated: May 27, 2008

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